This invention relates in general to projection color television systems and specifically to such systems wherein the viewing surface is remote from the projection CRT.
Large screen color television receivers are becoming increasingly popular, with many being housed in a single cabinet with a lens system for optically projecting images on a large viewing screen affixed to the cabinet. Such systems do not require "set up" for proper convergence of the three color images because the position of the projecting CRT's and the viewing screen is fixed during manufacture.
An increasing number of large screen projection television systems have the viewing screen remotely positioned with respect to the projecting CRT's and therefore need to be set up. Many of these systems are designed for projection on any large, flat, light-colored surface such as the wall of an ordinary home, although special reflective screens yield a substantial increase in brightness. In these systems, the distance between the projecting CRT's and the wall or viewing screen is critical since convergence of the different color images is necessary to produce an optimum picture for viewing.
The prior art solutions to setting up such systems have included specifying that the distance to the viewing surface be measured off, supplying a string or tape of proper length for locating the projector with respect to the viewing surface and providing a separate optical system for determining the proper distance by focusing a projected light pattern on the viewing surface. Each of the prior art systems is either cumbersome, inaccurate, expensive or difficult to use. None of them is economical, accurate and simple to use. Accordingly, there is a need in the art for a simplified method and apparatus for set up of a projection color television system for use with a remote viewing surface.